Electrical heating tvevice



T. C. RUSSELL.

ELECTRICAL HEATING DEVICE.

APPLICATION FILED MAR. 23. 1921.

1,419,309. Patented Jiine 13,1922.

UNlTED STATES PATENT OFFICE.

' THOMAS c. Boss's tit, or cmcaeo, I INOIS,

ELECTRICAL HEATfN nnvic'n Application filed March 23,1921. 'Serial No. 454,781.

To all whom it may concern:

Be it knownthat 1,.Tnonrss C. Russmin, a citizen of the United states anda resident of Chicago, in the county-of Cools/State of Illinois, haveinvented certain=new and useful Improvements in'ElectricaZl Heating Devices, of whichthe'following isaspecification.

My invention .relates. to electrical T heating devices, particularly to that class in which bare electrical resistancexconductors form the heating element.

The main objectrof my invention ishto provide improvedimeans for/readily receiving and supporting the various sections of :1 Continuous resistance conductor and for oi ficiently insulating such sections from each other. In accordance with my invention, a plurality'of skeleton sheet metal frames are supported on a base structure, each frame securing a sheet of mica having yertical slots or slits leading'to holes, the sections of the resistancecond'uctor, which is in the form of a helix, being then readily slip ed through the slits to be thereafter locked 'in the holes, this arrangement eliminating expensive special parts such as insulating bushings or thimbles and simplifying the process of applying the conductor sections in lace. "w" l I y inventionalso involves other features of construction and arrangement which all co-operate to produce a strong, simple but eflicient structure of a few arts which are securely held together in t e 'most simple manner. H

The various features of my invention are disclosed in the device illustrated on the accompanying drawings in which Fig. 1 is a plan View, ,7

Fig. 2 is an end view,

Fig. 3 is a side view of a section of one of the supporting frames,

Fig. 4 is a view of the other side of the frame of Fig. 3,

Fig. 5 is an enlarged vertical cross sectional view of one of these frames and Fig. (i is a sectional view on line 66, Fig. l.

The device shown on the drawings is a rectangular stove which can be used for toasting. cooking or other heating purposes. ()n the rectangular base plate 10 are sup ported the transversely extending resistance conductor supporting frames 11, the constructionand'arrangenient of these frames bein clearly shown in Figs. 3, 4 and 5. Each frame is formed of sheet metal and has'the openings '12'therein which are larger thanthe-transverse area of the resistance wirei'h'elix 113. Above the openings the metal of the fraiue is cut away to leave the pazssageways or slots 14 leading to the openings; On one side of each frame and extendinggacros the-openings and slots is a islfeet -15 o=mica or other-suitable insulating andgfire-proof material, thesheets ,being held in place-by bendingdown the upper edge section :16 of the frame against the stripasclearly-shown in Fig. 5. The mica sheet of *each 'frame' has the holes 1? therethrongh which are preferably concentric wit-hthe openings 12 in the frame, and at eacl'islot*':14 the mica'sheet has a slit 18, th s slits extending downwardly to the respective holes 17.- Through theseslits the wire-ofthe'resistance helix is forced downwardly into the holes 17, the slits closing up-after insertion of the wire to then lock the helix in-place. The resistance helix supporting frames may be secured in any SuItabIe mannerQ; As shown they are dcfiected laterall at their lower edges to provide bases 19 iiy means of which they may be secured to the base plate 10 by means of spot-welding or bymeans of rivets 20. 0n the structure shown the resistance elementis a sin le length of'resistancc helix of the desire resistance, and is arranged in'longitudinally extending rows or sections 8. At the slots 14 of the supporting frames the wire of the helix is pressed down through the slits 18 to the holes 17. the mica adjacentthe slits yielding during passage of thewirebntcomingitogethcr again after the wire reaches the holes 17 to thereafter lock the wire in such holes and prevent rising thereof through the slits. The openings 12 being much larger than the helix, there will be sufiicient extent of mica between the helix and the metal frame to prevent contact at any time of the helix with the frame. The helix supporting frames at the ends of the base 1( are cured to present their mica sheets on the outside so that the transverse sections s of the helix between the longitudinal sec tions 8 thereof will he insulated from the metal of the frames. The ends a and w of the resistance helix are secured to the elements and supporting frames thereonis preferably enclosed in suitable framework. The framework shown is rectangular and comprises the end sans-23- and' 24*"and the width and length equal to that of the supporting plate 10 so that such .plate may form the bottom of-the enclosing. structure. The ends and sides of the, framework may be conveniently secured together by angle members QT SPQlB-WBldQd or rivetedthereto and such members may-be extendeidow'n warclly to form legs for elevating the structure over the table. or other supportrto pers mit ventilation and to gue/rd againstefire. As a means for'supportm thmplatenlO-I have shown ,tonguesp28 de outjofithe le structures inwardly to form supports; on which the plate 10 may rest i l f :5 I preferably provide a grill 29, over, the heat-mg helix, which, as shown-, rests .on fthe frames 11 and is held thereonzby the ho1ri. zontal flanges 30 on the walls-oftheiencl'os ing framework. The rill is inserted ahead of the plate 10 wherea ter the tongues'28iare deflected against theplate10'.-to-lock;all the parts securely in position. I L 7:, The contact pins 21 and 22 extend through one of the end walls 23 and- 24 afroilrwihiich they are thoroughly insulatedwby insulating material 31, as plainly shown in F ig-.'1. 1

The holes 17 in the mica sheet could-be of larger or smaller diameter-than thefhelix. Preferably they are smaller so rthatiafter insertion of thehelix the sections swill' be more securely anchoredand ifihEi-I turns kept separated to prevent short ci-rcuiting. In prior structures where the helix must be threaded through insulating bushings or holes such secure anchorage'of the helix is impossible and the sections are too-free and are apt to vibrate and close-up at points when under heat. Threading of a long piece of helix back and forth through supports is a very tedious process. i-th mylarrangement however the 'helix sections are merely pressed down through the mica sheet slits to be thereafter securely anchored and well insulated. The mica is sufliciently yielding to "as follows: side walls 25 and 26',fthe frame beingof a;

,jl. I-nnneleotrical heating device, the combination of a supporting plate, a metallic frame set on edge on said plate-and having a plurality. '.of openings therethrough c0m municating with the upper edge of the frame s strip of mica secured on said frame and having holes in register withthe frame openings :but: smaller thannthe frame openings, said strip havingslitsvleadingfrom one edge thereof through said openings and to saidrholes :through. which a resistance wire may be'inserteditozsaid holes.

2. Inian electrical heating device, the combination of a sup ontirigubase, aametalilic frame secured; one 'g'eion'saiidbase andlhav ing; a plurality of openings therethrongh passageways connect-ingsaid openings t0- tl11e upper =edgeflof the frame, a strip of mica seouredagainsfi said fname and having holes re istering with- .saidwopenings but Smaller t an-sa-id openings,- said. strip having sliitsleading through said passageways land openings to said holes, a resistance-wire supported in said ,hole's, said'slits affording a means for forcing said wire through the mica to said holes.

3. A supporting structure for electrical heating wires comprising a frame having openings therethrough and 5 slots leading from said holesto an edge of the frame, .a strip of electrical insulating material supported on said frameiand having holesin register with the-frame openings, :said strip having slits registeringmi-thwthe )frame slots and extendingDf-rom' an edge of the strip to the holes therethrouglnihe material of said strip being yielding to resist but to-permit passage of thjewvires through said slots and into position in saidhole r i In witness whereof, I hereunto subscribe my name this 18 day o-f'March, AD. 1921.

THOMAS !C. RUSSELL.

,from-zthe upper edge thereof 

